The present invention relates in general to a pulse-time modulation (PTH) signal generator for generating signals at microwave, mm-wave and optical wavelengths.
As microwave and laser based communication systems employ signals of progressively higher and higher frequencies (e.g., in excess of 10 GHz), it becomes increasingly difficult to design oscillator circuits which can be switched on and off accurately as required in pulse-time modulation (PTM) communication schemes, such as pulse-width modulation (PWM) and pulse-position modulation (PPM). In PTM systems, the information transmitted on the signal is contained in the relative positions of modulated pulses as the signal is switched on and off, and the switching is typically achieved by switching the signal generating oscillator on and off. Such arrangements work fairly well at low frequencies, but are not readily implemented at very high frequencies due to adverse ambient effects and inherent limitations on oscillator switching speeds.